Municipal Water Leader
Interview

Northwest Pipe’s Perfect Pipe System: A Low-Maintenance Solution for Storm Water and Wastewater Conveyance

Perfect Pipe and the Perfect Lined Manhole are two new lined-concrete products manufactured by Northwest Pipe Company. Easy to install and maintain and with a long lifespan, these products promise long-term savings, and their corrosion resistance makes them ideal for conveying storm water or wastewater. In this interview, Heather Christensen, the technical marketing manager of Geneva Pipe and Precast, a Northwest Pipe Company; Scott Montross, the president and CEO of Northwest Pipe; and Mike Wray, the vice president and general manager of Geneva Pipe and Precast, tell Municipal Water Leader about the virtues of the Perfect line of products. 

 

Municipal Water Leader: Please tell us about Perfect Pipe and Perfect Lined Manhole. 

Mike Wray: Originally developed in Europe, Perfect Pipe is a gasketed, reinforced concrete pipe lined with high-density polyethylene (HDPE). Similarly, Perfect Lined Manhole is composed of a concrete manhole base and cone lined with fiber-reinforced plastic (FRP) and with HDPE-lined concrete risers. These concrete-HDPE and concrete-FRP composite products are a robust solution for storm water and wastewater conveyance systems. Our Geneva Pipe location in Orem, Utah, produces Perfect Pipe and the Perfect Lined Manhole System. 

Scott Montross: Our Perfect Pipe and Perfect Lined Manhole products are corrosion resistant and have high static load capacities, which makes them an ideal solution for conveying storm water or wastewater with corrosive properties in shallow or deep bury and high groundwater conditions. 

Mike Wray: The products offer the strength and longevity of rigid concrete pipe and the corrosion-resistant properties of HDPE in one composite system. Many project owners specify a casing pipe to handle loads and a carrier pipe to convey water or wastewater. These functions can now be performed by one pipe in one pass, saving project time and reducing costs. Suitable for use in both open-trench construction and trenchless installation, Perfect Pipe is versatile enough to satisfy diverse project requirements. 

Municipal Water Leader: Do you foresee customers using Perfect Pipe throughout an entire system, or only in specific sections? 

Mike Wray: Perfect Pipe can be used for complete projects or in specific locations where rough conditions are not conducive to the use of traditional pipe products. We have seen projects consisting of several miles of large-diameter pipe in environments ideal for HDPE-lined concrete. Perfect Pipe is also used in conjunction with alternate pipe materials in select locations along a project alignment where conditions are not suitable for the main system pipeline. Railroad and river crossings and high-traffic areas are examples of locations where Perfect Pipe may be a better solution. In many instances, Perfect Pipe is the right choice for 200–300 feet of the overall pipe requirements. 

Heather Christensen: The Perfect Lined Manhole is produced by forming a fiber-reinforced plastic liner to match the invert of a manhole base. The liner is then embedded in a monolithic form using self-consolidating concrete (SCC) to provide an impervious, uniform, and continuous plastic lining for the manhole base and walls. The manhole riser sections are also lined with HDPE, backed with a dense anchor pattern. A pressure-equalizing gasket ensures corrosion resistance across all joints. 

Perfect Pipe is produced by forming an HDPE cylinder that is welded together and expanded to match the joint profile. The plastic liner is then placed in the pipe form along with steel reinforcement. The form is filled with SCC, and the coupler is installed once the concrete cures. 

Municipal Water Leader: How does Perfect Pipe compare to other PVC and plastic liner options in terms of features and price? 

Heather Christensen: Both Perfect Pipe and Perfect Lined Manhole feature a joint design that eliminates the need for field welding for most diameters. This saves time and money in the installation process and ensures a quality connection. The Perfect Pipe internal connector provides an even transition across each joint to promote smooth, laminar flow. The connector also facilitates a gas- and watertight seal by compressing the pipe gaskets against the HDPE liner for a 36‑pound-per-square-inch (psi) pressure-resistant connection. 

The HDPE liner used in Perfect Pipe has one of the densest anchor patterns available, with over 150 anchors per square foot. Pairing this dense anchor pattern with SCC is another advantage over alternative liners that use dry-cast or conventional wet-cast concrete. The highly flowable nature of SCC allows it to fill all voids between the anchors of the HDPE liner, forming a secure connection between the liner and the concrete. HDPE also offers higher abrasion resistance than PVC alternatives. 

The premium quality of Perfect Pipe and Perfect Lined Manhole ensures a long-lasting solution to even the toughest project conditions and minimizes the potential need for system maintenance, repairs, or replacement within the products more-than-100‑year design life. Because of this, these products have lower life cycle costs than other liner solutions. Further savings result from the lower installation, operation, and maintenance costs of the system over its lifetime. 

Municipal Water Leader: Will field teams need to learn new installation techniques to work with Perfect Pipe or be certified to install it? 

Mike Wray: Another advantage of this system is its ease of installation. The interior Perfect Connector provides a tight seal and comes preinstalled on one end of the pipe. The installation crew simply pushes the pipe ends together until the coupler is fully engaged. Contractors familiar with installing concrete pipe will find Perfect Pipe simple to install. The Perfect Lined Manhole is installed like any other precast manhole. No certification is needed, and our field service team is ready to help with any questions. 

Municipal Water Leader: Please tell us about testing standards and results. 

Heather Christensen: We manufacture and assure the quality of Perfect Pipe and Perfect Lined Manhole to the requirements of the ASTM C76 and ASTM C478 standards. Hydrostatic joint testing has shown that Perfect Pipe can withstand pressures of up to 36 psi. The manhole joint has been hydrostatically tested to 13 psi. The HDPE liner has been tested for pull-out resistance from the concrete per the ASTM D7853 standard and passed at 30 psi backpressure. In addition, the HDPE liner’s individual anchor strength was tested for pullout resistance at 117 pounds per anchor. More product and material testing standards and results, such as those related to chemical and abrasion resistance, are available on our website or from our team. 

Municipal Water Leader: How can Perfect Pipe and Perfect Lined Manhole integrate into an existing wastewater system? 

Mike Wray: Recently, we produced a lined manhole to replace a decaying manhole in a sewer system in Vineyard City, Utah. The project involved tying new construction into an existing line extending from a pump station. The upstream pump station added turbulence and increased the rate of the microbial-induced corrosion that had caused the previous unlined manhole to decay. This lined manhole includes two 8‑inch SDR-35 and 14‑inch PVC C900 connections, a high-quality cast-in connector, and an integrated gasket. 

Our Geneva team provided support through all phases of this project, including by developing additional drawings, organizing a plant tour and training, and providing onsite installation guidance. When complete, the contractor noted that the installation, which did not require any field welds, was actually easier than installing a traditional unlined manhole. After installation, the structure was vacuum tested per the ASTM 1244 standard to verify that it met the city’s standard pressure requirements. 

Scott Montross: Perfect Pipe and Perfect Lined Manholes are practical, low-maintenance solutions for renewing the systems of municipalities and water and wastewater agencies. We look forward to working with regional engineers and municipalities as we demonstrate how the Perfect system offers a completely leak-proof, low-maintenance, and cost-effective sewer and storm water management solution. 

Heather Christensen is the technical marketing manager of Geneva Pipe and Precast, a Northwest Pipe Company. 

Scott Montross is the president and CEO of Northwest Pipe Company.

Mike Wray is the vice president and general manager of Geneva Pipe and Precast.

For more on Northwest Pipe, contact info@nwpipe.com.